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Individuals with A, AB, or B blood types may have a higher risk of developing pancreatic cancer, according to the results of a study published in the Journal of the National Cancer Institute.1

The pancreas is an organ that is surrounded by the stomach, small intestine, bile ducts (tubes that connect the liver to the small intestine), gallbladder, liver, and spleen. The pancreas helps the body to break down food and also produces hormones, such as insulin, to regulate the body’s storage and use of food.

Pancreatic cancer has one of the highest mortality rates of all cancers. It accounts for approximately 2% of all newly diagnosed cancers in the United States each year but 5% of all cancer deaths. Pancreatic cancer is often called a “silent killer” because its symptoms are usually not recognizable until it has advanced and spread outside the pancreas. As a result, the majority of pancreatic cancers are not diagnosed until they have reached advanced stages and are considered incurable. Research is ongoing to identify risk factors and genetic predisposition for this disease in the hopes of ensuring earlier diagnosis and higher cure rates.

In the current study, researchers evaluated data from 107,503 subjects from two large, prospective cohort studies: The Nurses’ Health Study (initiated in 1976) and the Health Professionals Follow-up Study (initiated in 1986). They found that the risk of pancreatic was lowest among individuals with blood type O. Compared with individuals with blood type O, those with blood type A have a 32% higher risk of developing pancreatic cancer, those with type AB have a 51% higher risk, and those with type B have a 72% higher risk.

To explore how genetic variation influences risk of pancreatic risk, researchers also conducted a genome-wide association study (GWAS).1 In this type of study, researchers assess common genetic variants known as single-nucleotide polymorphisms (SNPs) in people with and without disease.

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The researchers first studied the genomes of 1,896 patients with pancreatic cancer and 1,939 people without pancreatic cancer in order to identify SNPs that were more common in patients with pancreatic cancer. They then verified their results in additional groups of people with and without pancreatic cancer.

The results suggested that several SNPs on chromosome 9 were linked with pancreatic cancer risk. The part of chromosome 9 that was involved contains the ABO gene (the gene that determines blood type). People who had gene variants for A, B, or AB blood types were more likely to develop pancreatic cancer than people who had the gene variant for blood type O. These results are consistent with previous studies that have suggested a relationship between blood type and risk of pancreatic cancer.2

The results of these studies suggest that variations in the ABO gene influence risk of pancreatic cancer. With further research the association between blood type and the risk of pancreatic cancer may provide insight into the development of this deadly disease. The researchers concluded, “In two, large, independent populations, ABO blood type was statistically significantly associated with the risk of pancreatic cancer. Further studies are necessary to define the mechanisms by which ABO blood type or closely linked genetic variants may influence pancreatic cancer risk.”

References:

  1. Wolpin BM, Chan AT, Hartge P, et al. ABO blood group and the risk of pancreatic cancer. Journal of the National Cancer Institute. 2009; 101:424-431.
  2. Amundadottir L, Kraft P, Stolzenberg-Solomon RZ et al. Genome-wide association study identifies variants in the ABO locus associated with susceptibility to pancreatic cancer. Nature Genetics [early online publication]. August 2, 2009.